1. Field of the Invention
This invention relates to an apparatus and method for splicing together two threadlines in a manufacturing process and, more specifically, to a manually assisted apparatus and method resulting in a knot-induced twist entanglement splice that joins a threadline from a standby spool to the running threadline from an active spool.
2. Description of Background Art
There are certain manufacturing processes that rely upon a steady supply of a threadline or multiple threadlines of fiber, yarn, or filament. All such threadlines, however, are shipped in discrete packages (also referred to as thread spools), and connecting the trailing end of one package to the leading end of the next package becomes necessary.
U.S. Pat. No. 3,668,852 discloses an apparatus for automatically wrapping a splicing filament around the yarns to be spliced. U.S. Pat. Nos. 3,923,588 and 3,690,994 describe devices for thermally splicing thermoplastic yarns. All of the devices disclosed above require that the moving threadline be stopped in order to perform the splicing manipulation.
Published PCT Application WO 97/28079 discloses pressing and fusing two yarns which are placed in a crossing position. This method avoids having to stop the advancing threadline, but a complex mechanical buffer system is required to do so.
German Published Patent Application No. 33 36 202 discloses a device for interlacing filament yarns with an air splicer without interrupting yarn transport. This process, however, is limited to uncoalesced, multifilament threadlines.
U.S. Pat. No. 5,887,322 discloses an apparatus and method for splicing two threadlines with adhesive tape applied by a pair of counter-rotating adhesive applicators. This device requires coordination of components including alignment assembles, adhesive applicators, cutting knives and the unwinder through the use of timers, solenoids, and stepper motors with adjustable timings.
There exists a need for a simple, versatile, and reliable apparatus and method for splicing a moving threadline to another threadline. There is such a need especially for fibers that exhibit stretch properties, such as spandex.
The invention provides a method and apparatus for splicing threadlines using a knot. The threadlines are preferably elastic fiber, yarn or filament.
In a first embodiment, the invention provides a method for splicing an elastic thread comprising the steps of:
a. feeding a first elastic thread in a line or path between two guides under tension;
b. positioning a second replacement elastic thread substantially parallel to said first thread;
c. slip-knotting said second replacement elastic thread to encircle said first elastic thread with a loop of said second elastic thread without gripping said first elastic thread;
d. tightening the loop of step (c) in said second replacement elastic thread to grip said first elastic thread and to draw said replacement elastic thread along the path of said first elastic thread;
e. releasing tension on said first elastic thread by cutting so that the second elastic thread runs between the thread guides of step (a).
The invention further comprises a splicer comprising:
a. a pair of thread guides for positioning a running thread under tension;
b. a third thread guide for holding at least a portion of a replacement thread substantially parallel to and in alignment with said running thread;
c. a longitudinally slotted cylindrical thread holder for positioning a slip-knotted loop of said replacement thread around said running thread such that said slip-knotted loop and said running thread are initially held apart, such that when the slip-knotted loop is manually slipped off the slotted cylindrical thread holder and makes contact with the replacement thread, the replacement thread is then drawn through said slotted cylindrical thread holder along the line defined by the first elastic thread.
The splicer of the invention may optionally include means for cutting the running thread.